1. Field of the Invention
The present invention relates to an electromechanical actuator that has a screw mechanism and outputs linear driving force, and an actuator unit including an electromechanical actuator.
2. Description of Related Art
Conventionally, an electromechanical actuator having an electric motor and a screw mechanism has been used in various fields such as the field of aircraft. This electromechanical actuator converts rotational driving force that is output by the electric motor into linear driving force and outputs the converted driving force, using the screw mechanism. The electromechanical actuator drives various kinds of equipment by an output portion being displaced so as to extend and retract in a linear direction with respect to a housing.
With the aforementioned electromechanical actuator, there are cases where a jammed state occurs in the screw mechanism due to a cause such as prying or seizure. If a jammed state occurs in the electromechanical actuator, it becomes difficult to advance and withdraw the output portion with respect to the housing.
U.S. Pat. No. 5,214,972 discloses an electromechanical actuator provided with a first electromechanical actuator and a second electromechanical actuator. The first electromechanical actuator and the second electromechanical actuator are installed so as to coaxially extend in opposite directions. The first electromechanical actuator and the second electromechanical actuator each include an electric motor and a ball screw mechanism. In the electromechanical actuator having this configuration, even if a jammed state occurs in the screw mechanism in one of the first and second electromechanical actuators, the other one of the first and second electromechanical actuators is in an operable state. For this reason, in this electromechanical actuator, even if the aforementioned jammed state occurs, the output portion can be withdrawn to a position at which the output portion is retracted with respect to the housing.